Tube finishing machine



T. J. HENDERSON TUBE FINISHING MACHINE Feb. 9, 1954 2 Sheets-Sheet 1 Filed July 28, 1950 IWN M36 4 flrroeNt-YS .T. J.'HE NDERSON TUBE FINISHING MACH Feb. 9, 1954 INE .2 Sheets-Sheet 2 Filed July 28, 1950 Y Q HMHHH MMHHM H H I y Patented Feb. 9, [954 TI JBE FINISHING MAGHIN E Thomas J. Henderson, Dayton, Ohio, assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application July 28, 1950, Serial No. 176,402

1 Claim. 1

This invention relates to improvements in machines for finishing the interior surface of tubes particularly of the formed sheet metal and welded type.

It is among the objects of the present invention to provide a machine which, by the swaging process, finishes the interior surface of a metal tube with a smooth, burnished finish.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodi ment of the present invention is clearly shown.

Swaging machines as illustrated in the present drawings are purchasable in the open market and have been used for sizing and shaping metal tubes. For such operations ordinary cylindrically shaped mandrels or mandrels shaped to give finished tube the desired shape have been used. Swaging of the tube by these operations results in a matte or satin finish on the interior wall of the tube which finish is microscopically rough and uneven.

The present invention provides the ordinary swaging machine with a mandrel having alternately arranged or spaced undercut areas, such a mandrel giving the interior surface of a tube a burnished, mirror like finish instead of the matte, satin finish resulting from the use of a smooth, cylindrical mandrel.

In the drawings:

Fig. 1 is a part sectional, part diagrammatic view illustrating a standard swaging machine equipped with the present invention.

Fig. 2 is an end view of the machine shown in Fig. 1, certain parts being removed to illustrate interior features more clearly.

Fig. 3 is a schematic, full sized view of the mandrel, dies and die hammers of the machine equipped with the present invention.

Referring to the drawings, the standard swaging machine has a rotatable, hollow carrier or core journalled in the housing 2|. A pulley 22' is attached to the core 20, said pulley being drivingly connected to a pulley 23 by belts 24. Pulley 243 is attached to the drive shaft of motor 25 mounted upon housing 2| which has an extension providing a tubular hub in which a circular row of cammings rolls 26 are supported. The portion of the core extending coaxially into the circular space defined by rolls 26 has a diametral recess 30 in which the dies and die hammers are slidably supported. The two, oppositely disposed dies 3| and 32 have fiat outer surfaces, the opposite, inner surfaces being concaved to fit over and engage the tube 33 inserted into the machine for finishing purposes. Die Si is engaged by a hammer 35 in recess 39, the outer end of said hammer having a roll 36 adapted successively to engage the rolls 2G and be moved thereby to actuate die 31 into pounding engagement with tube, 33 for swaging purposes. Likewise die 32 is engaged by a hammer 3! provided with roll 38 which,

like roll 36, strkies the various rolls 2'6 as the core.

29 is rotated, thereby actuating the hammer 31 with each contact with a roll 28 to drive die 32 against the tube 33 with a swaging effect.

The feature of the present invention is the provision of a specially contoured mandrel 46 I held in the core 20 of the machine, within the confines of the two, oppositely disposed dies 31 and 32, by the rod ll. When tubes of substantial length, for instance 10 to 15 feet are machined, the outer end of rod 41 is detachably and rotatably supported on any suitable standard which maintains said rod in proper position relatively to the machine.

Fig. 3 illustrates the feature elements of the present invention at substantially full size for the machining of a tube approximately one inch inside diameter. As previously described, each die 3! and 32 has a fiat, exterior surface engaged by the respective hammers 35 and 3'! which, like the dies are slidably supported within the diametral slot or recess 30 in the core 20. The opposite, inner surface of each die is concaved, the arcuate surface fitting about and engaging the tube 33 to be machined. The outer or entrance end of each arcuated die surface is tapered as at 43 to facilitate insertion of the tube into the annular space between the mandrel 4t and the adjacent arcuated surfaces of the dies. The dies and hammers are substantially the same length which is shorter than the overall length of the mandrel d9.

Mandrel has a tapered outer end 42, the base of the tapered, or more specifically the full diameter mandrel portion, being adjacent the beginning of the tapers in the arcuated surfaces of the dies 3! and 32. The feature of the present invention resides in the provision of spaced undercut, annular areas or grooves in the surface of the mandrel 46 so that alternate areas are of different outside diameters. For purposes of this description the alternate, full diameter areas of the mandrel are indicated by A-C-E and G, the spaced undercut or smaller diameter areas being indicated by BD and F. For machining a tube having an inside diameter of approximately 1.001 inches, mandrel areas A-CE and G are substantially .990 inch in diameter. It will be noted that the areas A and G are the extreme, outer effective mandrel areas against which the tube is hammered. The undercut or smaller diameter areas BD and F are substantially .986 inch in diameter. Thus the larger diameter areas AC--E and G of mandrel 40 are substantially .011 smaller in diameter than the inside of the tube 33 while the undercut areas BD and F are .004 smaller in diameter than areas AC-E and G and substantially .015 smaller in diameter than the inside of tube 33.

It has been conclusively proven by tests, that the smoothest and most mirror like finish is obtained when the length of all or" the areas A to G inclusive vary. The variation of area lengths giving the most satisfactory results is progressively increasing the lengths of all of the areas, the shortest being adjacent the entrance end of the dies 3| and 32. The best results were obtained with a mandrel the area A of which was 1 .6875 inch long, B, .8125 inch long, C, 1 inch long, D, 1.125 inches long, E, 1.250 inches long, F, 1.375 inches long and G, 1.5 inches long. For tubes of larger inside diameter the diameter of the mandrel must, of course, be accordingly increased, however, when the inside diameter of the tube differs from the outside diameter of the mandrel .011 inch and the undercut areas such as BD and F are approximately .004 to .008 inch less in diameter than the adjacent larger areas such as A-CE and G, the lengths of all areas progressively increasing as in the present instance, then completely satisfactory results are obtainable.

Fig. 1 diagrammatically illustrates dual means for moving the tube in one direction through the machine longitudinally of the mandrel therein. Each means includes two grooved wheels 50 and which engage the tube, the wheel 50 being rotatably supported by any suitable bracket or standard 52 forming a part of or being attached to the machine. Wheel 51 is driven by suitable speed reducing, power transmitting mechanism driven by motor or any other suitable means. The drawings schematically show this mechanism to include a bevel gear 93 attached to wheel 5! and driven by a companion gear 54 mounted on shaft 55 to which a bevel gear 56 is secured which is driven by companion gear 57 mounted on an extension rod 58 connected with the drive shaft of motor 25. A similar mechanism is provided at the front of the machine to push instead of pull the tube through the machine. Any other power transmitting mechanism or driving apparatus may be used in conjunction with the swaging machine, as long as said mechanism moves the tube through the machine at the proper speed.

When processing or interiorly finishing a tube length, the tube is inserted into the machine, between dies 3| and 32 so that the tapered end 42 of the mandrel enters the tube. As the machine operates the hammers and 31 will re- '4 peatedly pound said dies inwardly of core 20 toward the axis thereof. As the tube 33 enters the annular space between the opposing dies and mandrel area or portion A these hammer blows through the dies will be directed against the tube and as the tube is moved through the machine the end thereof passes over the area or portion B which is undercut. The swaging action of the machine upon the tube as it passes over area A causes displacement or flowing of metal toward the undercut area B said tube region being again subjected to swaging at the area C when the tube enters the space about said mandrel area. This action continues successively throughout the entire length of the mandrel, the repeated swaging and metal displacement or flowing process, together with the continual movement of the tube longitudinally of the mandrel as well as its many periodic rotative movements due to rotation of the tube by the contacting dies, resulting in a burnishing like action which provides the treated interior surface of the tube with an extremely smooth and mirror like finish.

Variation in the relative dimensions of cooperating elements may be made within certain limits and satisfactory results attained, however, the. dimensions and arrangements here given provide for most satisfactory results.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

What is claimed is as follows:

' A burnishing mandrel consisting of a solid shaft, circular in cross-section and tapered at one end, said mandrel having alternate portions of a predetermined outside diameter and intermediate portions of a diameter predeterminately less than said alternate portions, the length of said alternate and intermediate portions progressively increasing predeterminately, starting from the portion adjacent the tapered end of the mandrel, the juncture of each of said portions presenting a substantially right angled shoulder forming a sharp annular edge at each end of said annular portion.

THOMAS J. HENDERSON.

References Gited in the file of this patent UNITED STATES PATENTS Number Name Date 424,213 Kellogg Mar. 25, 1890 439,951 l-Iendey Nov. 4, 1890 471,148 Shippee Mar. 22, 1892 588,649 Morse Aug. 24, 1897 835,729 Horton Nov. '13, 1906 953,616 Henrich Mar. 29, 1910 1,006,832 Day Oct. 24, 1911 2,025,439 Brownstein Dec. 24, 1935 2,058,556 Blair Oct. 2'7, 1936 2,239,085 Diescher Apr. 22, 1941 2,255,140 Waring Sept. 9, 1941 2,460,490 Cook Feb. 1, 1949 

